1. Field of the Invention
The present invention relates to a sampling apparatus designed precisely to aspirate, dilute and mix a small sample of fluid, such as a biological fluid which may be whole blood, serum, plasma, spinal fluid, etc., with a suitable diluent and deliver the resultant mixture to a scientific instrument for appropriate measurement or analysis thereby. The apparatus may be operated either in manual or automatic mode and is designed with capability to deliver the mixture at a place remote from the sample aspiration. The apparatus, furthermore, is designed to process a plurality of samples with no cross-contamination between the samples.
2. Description of the Prior Art
Admittedly, some parts of the sampling apparatus of the invention have been disclosed in the prior art, but nowhere has the combination of such an apparatus, nor some other parts, have even been hinted at, especially with the features and advantages as hereinbelow more fully described.
For instance, U.S. Pat. No. 3,900,289 that issued to Max D. Liston on Aug. 19, 1975, entitled "Apparatus and Method for Filling a Compartment," discloses basically a specimen dispenser designed to fill a compartment to a predetermined level with an aqueous solution taken from a reservoir. The dispenser includes a hollow probe nozzle designed to withdraw solution from the reservoir and is then moved to the vicinity of the compartment in order to deposit a predetermined amount of the solution into the compartment. It specifically discloses a carousel-type arrangement in which both the reservoir and the compartment are concentrically mounted in the carousel.
A further U.S. Pat. No. 3,858,450 that issued to Alan R. Jones on Jan. 7, 1975, entitled "Sample Mixing and Metering Apparatus," discloses a sampling head including a hollow pick-up probe for extracting a given amount of sample from a sample cup. The probe is movable between a sampling position and a retracted position. A valve mechanism connected to the probe is of the face-valve type in which two blocks are linearly slideable relative to one another between two valve positions, a sampling position and a delivery position. An air cylinder moves not only the probe but also operates this sliding valve. In the delivery position, the face-valve effects fluid connections for mixing a given amount of sample with another fluid and for delivering the mixture to a receptacle.
A further patent, U.S. Pat. No. 3,940,995, granted Mar. 2, 1976, to R. J. Harris Sr. et al., entitled "Automatic Fluid Injector," discloses an injector designed for accurately measuring and injecting quantities of fluid specimens into various media which may be a receptacle or an inlet of a scientific instrument. The injector essentially comprises three sub-assemblies including a syringe assembly, an injector feed assembly and a feed tray for transporting specimen-containing vials to the injector feed assembly. A reciprocable hollow probe associated with the injector feed assembly is designed to pick up a fluid specimen and convey the same to the syringe of the syringe assembly. Automatic contols are also disclosed for cyclically cleaning, purging, filling and injecting fluid specimens into an analytical instrument.